What is Lennox-Gastaut syndrome (LGS)?
Lennox-Gastaut syndrome (LGS) is one of the more severe forms of epilepsy. It usually develops during preschool years and is characterised by several seizure types and developmental delay. Seizures are generally difficult to control due to their resistance to anti-epileptic drugs.
What causes LGS?
Often no specific cause is identifiable, however, some of the known causes include:
In many instances, LGS is a sequel to infantile spasms which are sudden spasms or bending of the body, either at the trunk or neck. These usually commence between three and eight months, and may develop into the mixed seizure pattern,which characterises LGS, at two to three years.
There is also a number of rare childhood diseases which may lead to LGS..
How common is LGS?
It is estimated that LGS occurs in between three to eleven per cent of childhood epilepsies with slightly more males than females affected. The average age of onset is three years.
How is LGS diagnosed?
LGS is diagnosed by some or all of the following:
*An EEG is a graphic chart which displays electrical activity generated from the brain, recorded at the skin surface of the head.
What are the symptoms of LGS?
Seizures are always of several types and a child may experience some or all of these. The most common seizure types associated with LGS are tonic, atonic and atypical absence seizures. Periods of frequent seizures may be interspersed with periods of relative freedom from seizures. (Refer to the Seizure Types table for more information.)
Most children with LGS experience some degree of impaired intellectual functioning or information processing. In approximately 65 per cent of children with LGS, intellectual disability is evident, either previous to or at the time of diagnosis. In other children with LGS, intellectual disability becomes apparent within a year or two of the seizures beginning.
These include poor social skills and attention seeking behaviour. There are at least four possible causes:
Common seizure types
How is LGS managed?
Medication Anti-epileptic drugs (AEDs) are usually the best treatment for seizures although complete seizure control is rarely achieved. LGS often requires frequent changes in dose and type of medication, with some medications losing their initial effectiveness. Unlike most childhood epilepsies, the simultaneous use of more than one type of medication is often necessary.
The AEDs most commonly prescribed for LGS are listed in the table below. There are also a number of new AEDs currently being trialled in Australia and overseas, which appear to be achieving good results with LGS. This includes Lamotrigine.
Common AEDs prescribed for LGS
(Refer to the Epilepsy Medications brochure in this series for more information about commonly prescribed AEDs and possible side effects.)
A ketogenic diet is a special diet which has been clinically effective in reducing seizures. This type of diet was commonly used before the availability of modern anti-epileptic drugs but is rarely used today. It is very high in fat, often unpalatable and requires strict compliance.
In addition, the ketogenic diet elevates blood cholesterol levels markedly and is expensive to implement. It is not a long term proposition.
Vagus nerve stimulation
The vagus nerve stimulator is a device, similar in size to a heart pacemaker, which is implanted in the chest with a lead that passes up to the neck and is placed around the vagus nerve. This device stimulates the vagus nerve for about 30 seconds every 5 minutes and has been shown to improve seizure control in people with uncontrolled seizures. The device may take up to a year to show maximum benefit. This device requires an operation for insertion as well as for removal. The batteries require replacement approximately every 5 years which would entail further surgery.
Attention to seizure triggers
It is recognised that the frequency of seizures may be associated with the child's level of alertness. The child who is overexcited for example or lacks sufficient stimulation, may experience more seizures.
Therefore, a stimulating but stable environment can be important in reducing the number of daily seizures. This may include a strict routine of regular meals, sleep and medication.
Illness may also trigger seizures. For example, often seizure activity may increase just before the onset of high body temperature and fever. Vomiting and diarrhoea can also affect the body's ability to absorb medication.
Status epilepticus (status) occurs in about 50 per cent of people with LGS. It is the term used to describe prolonged seizures of 30 minutes or more or the occurrence of repeated seizures without regaining consciousness between attacks.
Status can occur with any type of seizure and is categorised as either convulsive or non-convulsive. Status can last from hours to days or in the case of non-convulsive status, even weeks or months. Factors which may lead to status include sudden withdrawal from medication, illness, fever and infections.
Status in children with LGS is most often non-convulsive. It is characterised by severe confusion, apathy or a `flat' mood, stupor or at worst, apparent dementia. Inconspicuous muscle spasms and greatly impaired balance and coordination are usually evident.
Convulsive status may ultimately lead to brain damage and death unless stopped quickly. Usually it is stopped by administrating rectal valium. Some parents and carers learn to administer rectal valium at home. This option would need to be discussed with your doctor.
What does the future hold for a child with LGS (prognosis)?
One parent comments: "Basically, I wanted to know what she would be like as an adult - that is how far I was looking forward as time goes on, your concerns come back a bit closer to the day-to-day"
To date, little research has been conducted into the prognosis of children with LGS. It is clear, however, that prognosis varies from child to child.
Generally, this syndrome is permanent. A few years after diagnosis, the epilepsy which was initially so difficult to control, may become less of an issue but impaired intellectual functioning and behavioural problems frequently persist. Complete recovery with freedom from seizures and normal development, is very unusual for the child with LGS.
(to help carers support the child with LGS)
Coping with LGS
In the words of parents themselves
Uncontrolled Epilepsy Parents' Support Group
The Epilepsy Foundation of Victoria Incorporated coordinates a support group for parents and carers of children with LGS and other forms of uncontrolled epilepsy.
Daytime and evening meetings are held in Camberwell and often include professional speakers.
Those who are unable to attend meetings can be included on the mailing list which is comprised of some 100 families from around Australia and other countries across the world.
For more information, contact the Epilepsy Foundation of Victoria (03) 9813 2866 Fax (03) 9882 7159 Toll-free 1300 852 853
Published by the EFV Medical consultant: Dr Ian Hopkins (courtesy Royal Childrens Hospital, Melbourne)
Copyright © 2001 Epilepsy Foundation of Victoria All rights reserved. This information may be reproduced for not-for-profit purposes provided its source is appropriately acknowledged. Please read our